So i have a 99 or 00 polaris scrambler 500 4x4. So I go to ride it the other day and I notice when I get on the throttle hard it makes a loud grinding noise. Thought maybe it was a chain slipping. So I tighten up the chains and I still hear it. I noticed that when I put it into reverse it dosnt make the noise, no matter what I do. So as the day progresses the noise gets worse. Everytime I hit the gas just the smallest bit it makes this grinding noise. So I keep riding it because I'm miles away from home and I'm with about 30 friends on a huge ride. The sound hasnt gotten any louder by now but when I stop it makes the noise but goes away when I let off the brake and let the fourwheeler roll on its on idle. Is it one of the gears in the trans.? A chain in there? Somthing I can fix cheaply. I'm mechanically inclined and have the book on it, but thought I would ask before I go tearing the trans apart. Any chance it could be one of the drive pullys? Thanks Adam

 

I would jack it up and see what turns in 2&4 wheel drive, that may help pinpoint the problem

 

Pull the clutch cover - see if you are grinding the primary clutch into the plastic cover.

This is usually the result of overheating the clutch and making the cover soft enough to sag at one point. It can be from a worn out belt (Excessive slipping), damaged or broken clutch springs, damaged or broken primary weights, trying to tow something too heavy, or trying to peel out while holding the brakes very firmly.

A broken clutch spring or damaged/broken weights could also make that noise, but my money is on the cover itself - and your primary rubbing on it.

 

its the silent chain in the gearcase. its normal but it gets sped up when there is no oil in the gearcase.
it wont do it in reverse because there are two gears that mesh together for reverse. in forward, it is a chain from one gear to another. thats why you only hear it in forwards and not in reverse.

not too bad of a job to do but you have to pull the gearcase out of the frame.

 

it could be as simple as a front sprocket missing some teeth. but if not, then you might be looking at taking the tranny out and taking it apart. if your mechanically inclined, and have a service manual, its pretty easy. theres a forward and a reverse chain inside.

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